Systems and methods for multiple analyte analysis

ABSTRACT

Systems and methods for multiple analyte analysis are provided. In one embodiment, a method includes determining concentrations of first and second analytes in a sample. The first and second analytes may be, for example, glucose and hydroxybutyrate. In this form, an indication related to the measured concentration of hydroxybutyrate is provided in response to determining that the concentration of hydroxybutyrate is above a predetermined value. In a further aspect of this form, a quantitative indication representative of the measured glucose concentration is automatically provided regardless of the value of the measured glucose concentration. In another embodiment, a system includes a meter configured to interact with a test element to assess first and second analytes in a sample. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the description and drawings.

BACKGROUND

The use of disposable test elements has become commonplace to measurethe presence and/or concentrations of selected analytes in test samples.For example, patients suffering from diabetes and similar medicalconditions often engage in self-monitoring of blood glucose where thepatient monitors his or her blood glucose levels. The purpose ofmonitoring blood-glucose levels is to determine the concentration level,and if necessary to take corrective action if the level is too high ortoo low in order to bring the level back within an acceptable range. Inaddition, blood glucose levels are determined to calculate a pre-mealinsulin bolus often with the help of a bolus calculator with the goal ofminimizing glucose increases from consumption of the meal. The failureto take corrective action can have serious medical implications. Glucosemonitoring is a fact of everyday life for diabetic individuals, and theaccuracy of such monitoring can literally mean the difference betweenlife and death. Failure to maintain blood glucose at acceptable levelson a regular basis can result in serious diabetes-related complications,including cardiovascular disease, kidney disease, nerve damage andblindness.

People with diabetes who intensively manage their blood sugar experiencelong-lasting benefits. The Diabetes Control and Complications Trial(DCCT) was a clinical study conducted from 1983 to 1993 by the NationalInstitute of Diabetes and Digestive and Kidney Diseases (NIDDK). TheDCCT compared intensive to conventional treatments. Patients onintensive treatment kept glucose levels as close to normal as possiblewith at least three insulin injections a day or an insulin pump, andfrequent self-monitoring of blood glucose levels. Intensive treatmentaimed to keep hemoglobin A1c (HbA1c), which reflects average bloodglucose over a 2- to 3-month period, as close to normal as possible.Conventional treatment consisted of one or two insulin injections a daywith once-a-day urine or blood glucose testing. The results of the DCCTstudy showed that keeping blood glucose levels as close to normal aspossible slows the onset and progression of eye, kidney, and nervediseases caused by diabetes. In fact, it demonstrated that any sustainedlowering of blood glucose helps, even if the person has a history ofpoor control.

A number of analytical instruments or biosensors, such as glucosemeters, are currently available that permit an individual to test theglucose level in a small sample of blood. Many of the meter designscurrently available make use of a disposable test element which, incombination with the meter, measures the amount of glucose in the bloodsample electrochemically or optically. In current glucose meters, theinformation displayed as a consequence of a successful blood glucosemeasurement is the respective blood glucose value, typically shown inmg/dL or mmol units, and perhaps the time and date the measurement wasperformed. This information, in combination with calculation of plannedor known intake of carbohydrates or planned or known activities andknowledge of other situational or individual factors, is in most casessufficient to allow diabetics to adjust or derive their dietary intakeand/or an immediate dose of insulin to inject to control blood glucoselevel on the short-term. Also, in case of low glucose values, diabeticscan detect the need for intake of sugar to avoid hypoglycemia.

An absence or insufficient amount of insulin prevents the body fromusing glucose as a fuel source to produce energy. When this occurs, thebody produces energy by breaking down fatty acids, which results inketone byproducts and increased ketone levels. Increased ketone levelsin diabetics may also be caused by a heart attack, stroke, recreationaldrug usage or an intercurrent illness such as pneumonia, influenza,gastroenteritis, or a urological infection. Excessive ketone levels indiabetics leads to an episode of diabetic ketoacidosis (DKA), a medicalemergency that can result in death if not treated. Symptoms of DKAinclude nausea, vomiting, excessive thirst and urine production,abdominal pain, labored breathing, fatigue, and coma, amongst others.Given the seriousness of DKA, it is desirable to administer treatment toreduce ketone levels before the full onset of a DKA episode. Further,since symptoms related to a DKA episode may not present until the DKAepisode has onset or ketone levels are otherwise undesirably high, it isgenerally preferred for ketone reducing treatment not to begin as aresponse to these symptoms.

Prevention of DKA episodes can be achieved by measuring ketone levelsand seeking medical attention if they rise above a certainconcentration. The ADA website recommends that ketone levels should bechecked every 4-6 hours when a diabetic has an illness (such as a coldor the flu), or when his or her blood glucose is more than 240 mg/dl.(Seehttp://www.diabetes.org/living-with-diabetes/complications/ketoacidosis-dka.html).Urine tests can be utilized to determine ketone levels. However, fordiabetics who perform multiple blood glucose tests per day, performingseparate urine tests in addition to their blood glucose tests is timeconsuming and burdensome.

By having a dual test to measure glucose and ketone levels on the sametest strip, a diabetic is better enabled to comply with testingrecommendations and safer therapy by detecting high ketone levels early.For example, it is recommended to avoid exercise when ketone and bloodglucose are high because elevated levels of these analytes may beindicative of unsatisfactory diabetes management. However, mostdiabetics do not have ketone tests readily available for testing, andoften do not have information readily available for how to handle suchsituations. Furthermore, the symptoms of diabetic ketoacidosis usuallyevolve over about a 24 hour period, meaning useful information andinstruction typically require the perspective of trending analysis.

The use of separate urine tests for determining ketone levels alsorequires additional diagnostic supplies and their attendant costs, andmakes it difficult to correlate blood glucose and ketone levels. It isalso possible to determine ketone levels from blood samples. When bloodsamples are used, ketone levels are commonly determined by measuring theconcentration of hydroxybutyrate, which is the predominate ketone inblood. Hydroxybutyrate concentrations below 0.6 mM in blood areconsidered normal, while hydroxybutyrate concentrations that are between0.6 mM and 1.5 mM indicate that a problem may develop and greater than1.5 mM indicate a risk for developing DKA. Hydroxybutyrateconcentrations above 3 mM in blood are indicative of DKA and requireemergency medical treatment.

Current techniques for determining ketone levels from blood involvesingle function test elements that are suitable for detectinghydroxybutyrate concentrations for example. Much like the urine testdescribed above however, diabetics who perform a relatively highmagnitude of blood glucose tests per day may find it time consuming andburdensome to perform separate ketone level blood tests in addition totheir blood glucose tests, particularly since current blood ketone testsare slower than state of the art blood glucose tests. Ketone level bloodtests that are performed independent of blood glucose tests also requireadditional diagnostic supplies and additional expenses attendanttherewith must be incurred. Moreover, performing separate tests fordetermining blood glucose and blood ketone levels makes it difficult tocorrelate the measured blood glucose and blood ketone values since,amongst other factors, they may not be measured within the sametimeframe or may be performed using different devices.

Other techniques for determining ketone levels from blood involve testelements suitable for detecting blood glucose and blood ketone levels.In these current test elements however, blood glucose levels aremeasured more quickly than blood ketone levels such that the bloodketone test results are delayed and provided after the blood glucosetest results. Alternatively, the results of both the blood glucose andblood ketone tests are not provided until the latter completion of theblood ketone test. In either case, waiting for the results of one orboth tests until the blood ketone test is completed can become quiteburdensome and time consuming for a diabetic who performs a relativelyhigh magnitude of tests each day, particularly when considering that insome instances the blood ketone test can take almost twice as long tocomplete as the blood glucose test. Moreover, when the blood glucosetest results are provided before and separate from the blood ketone testresults, a possibility arises for a user to discontinue testing beforethe blood ketone test is completed and/or divert attention elsewhereafter the blood glucose test results have been provided but before theresults of the blood ketone test have been properly considered. Infurther instances, a user may be burdened by the automatic display ofthe blood ketone results following each test, which may lead toinsufficient consideration or user depreciation of the importance of theblood ketone test results. As a corollary, burdening a diabetic patientwith a ketone value for each measurement even when the majority of timeit is in a normal range could cause a user to ignore the value at a timewhen it really requires attention.

Given the ramifications of accurate recording, reporting and analyzingof blood ketone measurements in addition to blood glucose measurements,improvements in the techniques, procedures and equipment for testingblood ketone levels and/or blood ketone and blood glucose levels aredesired.

SUMMARY

Systems and methods for multiple analyte analysis are provided. In oneembodiment, a method includes determining concentrations of first andsecond analytes in a sample. The first and second analytes may be, forexample, glucose and a ketone such as hydroxybutryate. For reference inthis application, the term “ketone” is understood to refer to andinclude ketone bodies such as hydroxybutyrate. In this form, anindication related to the measured concentration of hydroxybutyrate isprovided in response to determining that the concentration ofhydroxybutyrate is above a predetermined value. In a further aspect ofthis form, a quantitative indication representative of the measuredglucose concentration is automatically provided regardless of the valueof the measured glucose concentration. In a yet further aspect, eachmeasured concentration of hydroxybutyrate is stored or otherwiseretained regardless of whether that measured concentration is above apredetermined value in order to permit trending analysis to be conductedwith respect to all measured concentrations of hydroxybutyrate. Inanother embodiment, a system includes a meter configured to interactwith a test element to assess first and second analytes in a sample.Other aspects of the subject application are directed to uniquetechniques for analyzing analytes in a sample. Further embodiments,forms, objects, features, advantages, aspects, and benefits shall becomeapparent from the description and drawings.

In an additional embodiment, a method includes providing a test elementconfigured for analyzing first and second analytes in a sample;contacting the test element with the sample; determining concentrationof the first analyte in the sample and providing an indication inresponse to determining the first analyte concentration is above apredetermined value; and determining concentration of the second analytein the sample. In one form, the method further includes displayinginformation corresponding to the second analyte concentration. Inanother form, the first analyte is hydroxybutyrate and the secondanalyte is glucose. In still another form, the predetermined value is0.6 mM. In another form, the step of providing the indication inresponse to determining the first analyte concentration is above apredetermined value includes at least one of displaying the firstanalyte concentration, providing a warning, providing a list of actionsto take in response to the first analyte concentration being above thepredetermined value, and transmitting a message to at least one of auser of the test element, healthcare provider, caregiver and parent orguardian.

In yet another form of this embodiment, providing the indication inresponse to determining the first analyte concentration is above thepredetermined level includes transmitting a message to a mobile deviceor computer. In one aspect of this form, providing the indication inresponse to determining the first analyte concentration is above thepredetermined level further includes displaying a message related to thefirst analyte concentration on a test meter. In another form, providingthe indication in response to determining the first analyteconcentration is above the predetermined level includes displaying amessage related to the first analyte concentration. In one other form,providing the indication in response to determining the first analyteconcentration is above the predetermined level includes changing a coloror a shading of at least a portion of a display screen or textualdisplay. In still another form, providing the indication in response todetermining the first analyte concentration is above the predeterminedlevel includes displaying an information icon on a display screen. Instill another form, providing the indication in response to determiningthe first analyte concentration is above the predetermined levelincludes displaying an information icon on a display screen with anaudio tone or vibration to encourage the patient to take notice. In oneaspect of this form, the method further includes providing a message inresponse to a selection of the information icon. In a further aspect,the message includes at least one of a description of the first analyteconcentration, a list of actions to take in response to the firstanalyte concentration being above the predetermined level, and contactinformation of a healthcare provider.

In another embodiment, a system includes a test element configured foranalyzing first and second analytes in a sample. The system alsoincludes a meter configured to interact with the test element andincluding a controller structured to: determine concentration of thefirst analyte in the sample and, if the concentration of the firstanalyte is above a predetermined value, provide a first signal forproviding an indication related thereto; and determine concentration ofthe second analyte in the sample and provide a second signal foroutputting information related to the concentration of the secondanalyte. In one form of this embodiment, the indication includes atleast one of outputting information corresponding to the concentrationof the first analyte, providing a warning, providing a list of actionsto take in response to the first analyte concentration being above thepredetermined value, and transmitting information related to theconcentration of the first analyte to at least one of a user of thesystem, healthcare provider, caregiver and parent or guardian. Inanother form, the first analyte is hydroxybutyrate and the secondanalyte is glucose. In one aspect of this form, the predetermined valueis in the range of 0.5 mM to 3.0 mM.

In another form of this embodiment, the meter further includes a displayresponsive to the first signal to display the indication related to theconcentration of the first analyte. In one aspect of this form, thedisplay is responsive to the first signal to provide an icon related tothe concentration of the first analyte. In another aspect of this form,at least a portion of the display is configured to change color orshading in response to the first signal. In yet another aspect of thisform, the display is configured to provide an information icon inresponse to the first signal. In a further aspect, the display isfurther configured to provide a message in response to a selection ofthe information icon, the message including at least one of adescription of the first analyte concentration, a list of actions totake in response to the first analyte concentration being above thepredetermined level, and contact information of a healthcare provider.In still another form of this embodiment, the meter further includes acommunication module configured to transmit a message to a mobile deviceor computer in response to the first signal. In yet another form, thecontroller is further structured to provide a third signal for providingan approval indication if the concentration of the first analyte isbelow the predetermined value.

In a further embodiment, a method includes performing a plurality oftests to determine concentrations of first and second analytes in asample. Each of the tests includes applying the sample to a test elementconfigured for analyzing the first and second analytes in the sample.The method also includes storing the first analyte concentrationdetermined from each test performed; analyzing the stored concentrationsof the first analyte to monitor for an existence of any trends in thestored concentrations, such as toward a predetermined value or upwardlyincreasing over time, or as between common time periods such as specifictime of day, weekend trends, or after specific events like meals,exercise or illness, and any interesting rate-of-change trendssuggesting concerning changes in ketone/hydroxybutyrate levelsregardless of whether any such levels are measured to be above apredetermined value; and providing a first indication in response todetecting the existence of the trend. The rate-of-change value totrigger a trend can be a preselected value or one that can be set by aperson with diabetes or health care providers within reasonable ranges.In one form, the method also includes providing a second indication inresponse to determining the first analyte concentration is above thepredetermined value in any one or more of the plurality of tests. In oneaspect of this form, the method further includes automatically providinga third indication related to the concentration of the second analyteafter performing each of the tests. In a further aspect, the firstanalyte is hydroxybutyrate and the second analyte is glucose.

In another form of this embodiment, the first indication includes one ofa graphical illustration of the trend and an information icon. In stillanother form, providing the first indication includes displaying aninformation icon on a meter display. In another form, the method furtherincludes providing a graphical illustration of the trend in response toa selection of the information icon. In another form of this embodiment,a graphical illustration of a trend is shown automatically if the trendmeets some pre-specified criteria. Such criteria could be for example:one or more measured values coming close to or exceeding a pre-specifiedhydroxybutyrate value, the max/min hydroxybutyrate level over the pastdays/weeks/months is greater than a pre-specified value, or othercriteria such as initiation of a “ketone watch” or measured valuestrending toward initiation of a “ketone watch”.

A ketone watch may be set by the meter whenever a measured glucose valuegreater than or equal to a predetermined value, such as 240 mg/dL, isrecorded. The ketone watch would recommend testing glucose andhydroxybutyrate every 4-6 hours as long as the glucose value exceeds thepredetermined value. In one non-limiting form for example, uponinitiation of and during the ketone watch, the meter may automaticallydisplay measured glucose and hydroxybutyrate levels regardless of theirrelationship with any pre-specified values. A ketone watch may alsostart a new trending set of data to determine if hydroxybutyrate levelsare beginning to rise even if still below the threshold of a highhydroxybutyrate level. A ketone watch may also be started if the userhas indicated they have an illness such as a cold or the flu.

In still another embodiment, a method includes providing a hand helddevice including a display, a processor and a storage memory. The deviceis operative to engage one or more test elements and to determineconcentration of at least first and second analytes in a fluid sampleprovided on the one or more test elements. The method also includes:using the device, recording in the storage memory the value of thedetermined concentration of each of the at least first and secondanalytes; using the device, determining whether the determinedconcentration for the first analyte is above a first predeterminedvalue; using the device, determining whether the determinedconcentration for the second analyte is above a second predeterminedvalue; and using the device, activating a watch mode when the determinedconcentration for either of the first and second analytes is above therespective first and second predetermined values.

In one form of this embodiment, the storage memory includes a pluralityof recorded values of determined concentrations for each of the firstand second analytes, and the method further includes: selecting at leastone of the first and second analytes for monitoring trendinginformation; using the device, determining whether the trendinginformation for the analyte selected for monitoring generally matchespredetermined criteria for recommending an increased frequency fordetermining the concentration for the analyte selected; and using thedevice, activating the watch mode regardless of the determinedconcentration for either of the first and second analytes being abovethe respective first and second predetermined values when the trendinginformation generally matches the predetermined criteria. In one aspectof this form, the first analyte is hydroxybutyrate and the secondanalyte is glucose, and the analyte selected for monitoring compriseshydroxybutyrate.

In another form of this embodiment, the watch mode comprises the deviceproviding at least one recommendation for an increased frequency fordetermining the concentration for at least one of the first and secondanalytes. In yet another form, the method further includes, when thewatch mode is activated, displaying a visual indication on the display,the visual indication configured to indicate the activation of the watchmode. In another form of this method, the first analyte ishydroxybutyrate and the second analyte is glucose. In one non-limitingform, one or more of the embodiments described above may involve a testelement that includes a first coenzyme-dependent enzyme or a substratefor the first enzyme and a second coenzyme-dependent enzyme or asubstrate for the second enzyme. The test element also includes acoenzyme selected from the group consisting of thio-NAD, thio-NADP, anda compound according to formula (I):

in which

A=adenine or an analog thereof,

T=in each case independently denotes O or S,

U=in each case independently denotes OH, SH, BH₃ ⁻, or BCNH₂ ⁻,

V=in each case independently denotes OH or a phosphate group,

W=COOR, CON(R)₂, COR, or CSN(R)₂ in which R in each case independentlydenotes H or C₁-C₂-alkyl,

X₁, X₂=in each case independently denote O, CH₂, CHCH₃, C(CH₃)₂, NH, orNCH₃,

Y=NH, S, O, or CH₂,

Z=a residue comprising a cyclic group with 5 C atoms which optionallycontains a heteroatom selected from O, S and N and optionally one ormore substituents, and a residue CR4₂ wherein CR4₂ is bound to thecyclic group and to X₂, and

where R4=in each case independently denotes H, F, Cl, or CH₃, providedthat Z and the pyridine residue are not linked by a glycosidic bond,

or a salt or optionally a reduced form thereof.

In one aspect, the first analyte is hydroxybutyrate and the first enzymeis a hydroxybutyrate dehydrogenase. In a further aspect, thehydroxybutyrate dehydrogenase is 3-hydroxybutyrate dehydrogenase. In afurther aspect, the second enzyme is a dehydrogenase selected from thegroup consisting of glucose dehydrogenase, lactate dehydrogenase, malatedehydrogenase, glycerol dehydrogenase, alcohol dehydrogenase, sorbitoldehydrogenase, and an amino acid dehydrogenase comprising L-amino aciddehydrogenase. In still another aspect, the second analyte is glucoseand the second enzyme is a glucose dehydrogenase or a glucose oxidase.In a further aspect, the coenzyme is a compound according to formula (I)

in which

A=adenine,

T=in each case denotes O,

U=in each case denotes OH,

V=in each case denotes OH,

W=CON(R)₂ in which R denotes H,

X₁=O,

X₂=O,

Y=O, and

Z=a carbocyclic 5-membered ring of the general formula (II)

in which a single bond is present between R5′ and R5″, and in which

R4=H,

R5′=CHOH,

R5″=CHOH,

R5=CR4₂,

R6=CH, and

R6′=CH.

In yet another further aspect, the coenzyme is a compound according toformula (I)

in which

A=adenine,

T=in each case denotes O,

U=in each case denotes OH,

V=in a first case denotes OH and in a second case denotes a phosphategroup,

W=CON(R)₂ in which R denotes H,

X₁=O,

X₂=O,

Y=O, and

Z=a carbocyclic 5-membered ring of the general formula (II)

in which a single bond is present between R5′ and R5″, and in which

R4=H,

R5′=CHOH,

R5″=CHOH,

R5=CR4₂,

R6=CH, and

R6′=CH.

In still another further aspect, the coenzyme is thio-NAD. In anotherfurther aspect, the coenzyme is thio-NADP.

In a further aspect, the test element includes a first reagent materialwhich includes the first enzyme or the substrate for the first enzyme,and the coenzyme selected from the group consisting of thio-NAD,thio-NADP and the compound according to formula (I) or a salt oroptionally a reduced form thereof. In a further aspect, the test elementalso includes a second reagent material which includes the second enzymeor the substrate for the second enzyme, and a coenzyme selected from thegroup consisting of FAD, NAD, NADP and the compound according to formula(I) or a salt or optionally a reduced form thereof. In a further aspect,the test element includes a test strip configured to carry the first andsecond reagent materials. In yet another further aspect, the test stripincludes a first electrode system associated with the first reagentmaterial and a second electrode system associated with the secondreagent material. In another aspect, the first reagent material furtherincludes an electrochemical mediator or mediator precursor such as oneof nitrosoaniline, potassium ferricyanide, a phenazine derivative, orhexaammineruthenium chloride or a combination thereof.

Further, although the description hereof discloses the use of aconvenient dual test of ketone and glucose, persons of skill in the artwill appreciate that other multi-analyte test strips may also bebeneficial as a dual test with glucose and analytes such as 1,5anhydroglucitol or HbA1c.

Another aspect of the present application is a unique technique formeasuring the presence and/or concentration of multiple analytes in testsamples. Other aspects include unique methods, systems, devices, kits,assemblies, equipment, and/or apparatus related to analyte detection ina sample.

Further aspects, embodiments, forms, features, benefits, objects, andadvantages shall become apparent from the detailed description andfigures provided herewith.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a first embodiment test element.

FIG. 2 is an exploded, perspective view of various features of the testelement of FIG. 1.

FIG. 3 is an exploded, perspective view of a second embodiment testelement.

FIG. 4 is a fragmentary, sectional view of the test element of FIG. 3.

FIG. 5 is a schematic illustration of an analytical instrumentstructured for use with the test element of FIG. 1.

FIGS. 6A-6B are schematic illustrations of one non-limiting displayconfiguration for the analytical instrument.

FIGS. 7A-7B are schematic illustrations of another non-limiting displayconfiguration for the analytical instrument.

FIG. 8 is a schematic illustration of yet another non-limiting displayconfiguration for the analytical instrument.

FIG. 9 is a schematic illustration of the analytical instrumentcommunicating with other devices.

FIGS. 10A-E are schematic illustrations of another display configurationfor the analytical instrument.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

Systems and methods for multiple analyte analysis are provided. In oneembodiment, a method includes determining concentrations of first andsecond analytes in a sample. The first and second analytes may be, forexample, glucose and hydroxybutyrate. In this form, an indicationrelated to the measured concentration of hydroxybutyrate is provided inresponse to determining that the concentration of hydroxybutyrate isabove a predetermined value. In a further aspect of this form, aquantitative indication representative of the measured glucoseconcentration is automatically provided regardless of the value of themeasured glucose concentration. In another embodiment, a system includesa meter configured to interact with a test element to assess first andsecond analytes in a sample. This assessment may range from detectingthe presence of the first and second analytes to determining theconcentration of the first and second analytes. Further aspects andfeatures of the present application are described with respect to theillustrated embodiments as follows.

Referring to FIGS. 1 and 2, further details of a first embodiment testelement 10 configured for assessing first and second analytes in asample will now be provided. Test element 10 is provided as anelectrochemical sensor including a sample-receiving chamber for thesample fluid, and first and second reagent materials for producingelectrochemical signals in the presence of the first and secondanalytes. In the illustrated form, test element 10 extends between ameter insertion end 12 and a dosing end 14. In one non-illustrated form,the shape of dosing end 14 may be distinguishable from meter insertionend 12 so as to aid users in proper handling and use of test element 10.Test element 10 may also include one or more graphics (not shown) toprovide a user guidance on proper handling and use.

Test element 10 is provided in the form of a disposable test strip whichhas a laminar construction including a base substrate 16, a spacinglayer 18, a body cover 20 and a chamber cover 22. Further details oftest elements including a similar laminar construction are provided inU.S. Pat. No. 7,727,467, the contents of which are incorporated hereinby reference in their entirety. Spacing layer 18 includes a void portion24 to provide a sample-receiving chamber 26 extending between basesubstrate 16 and body cover 20 and chamber cover 22. In thisconfiguration, sample-receiving chamber 26 opens at dosing end 14 oftest element 10 through an opening 28 which is configured to facilitatepassage of a sample fluid into sample-receiving chamber 26. Forms inwhich sample-receiving chamber 26 opens through an opening positionedalong a side of test element 10 are also contemplated. Further, forms inwhich the sample-receiving chamber 26 opens through an openingpositioned along the full length or width of the dosing end 14 andincluding a portion of the sides are also contemplated.

Body cover 20 and chamber cover 22 overly spacing layer 18 and define aslot 30 therebetween which provides a vent opening communicating withsample-receiving chamber 26 to allow air to escape sample-receivingchamber 26 as a sample fluid enters sample-receiving chamber 26 throughopening 28. Slot 30 is located at a position relative tosample-receiving chamber 26 that is interior of the location of theelectrode systems (described below) positioned in sample-receivingchamber 26. Sample fluid entering sample-receiving chamber 26 willprogress as far as the vent opening, but no further. When viewed fromthe top, the slot provides a visual indication of a “fill-line” toconfirm that the electrode systems in sample-receiving chamber 26 havebeen properly wetted or covered to function properly. Additionally oralternatively, dose sufficiency electrodes may also be positionedadjacent slot 30 to detect when the sample fluid has progressed to slot30 to assure that wetting of the measuring electrodes has occurred.Other alternative configurations of test strip architectures are alsoanticipated that would include the required electrodes for two assaysand the application of a sample with means for venting. The alternativearchitectures may include additional features such as means fordetecting sample sufficiency or other electrodes for corrections orfailsafes.

Other than the electrode systems and reagent materials, sample-receivingchamber 26 may be empty or may alternatively include a sorbent material.Suitable sorbent materials include polyester, nylon, cellulose, andcellulose derivatives such as nitrocellulose. When included, a sorbentmaterial helps facilitate uptake of the sample fluid by assisting inwicking the fluid into sample-receiving chamber 26. The use of a sorbentmaterial would also serve to further reduce the void volume ofsample-receiving chamber 26 for reception of the sample fluid. In oneform, the filling of sample-receiving chamber 26 occurs by capillaryaction. The filling of sample-receiving chamber 26 can also be augmentedby other means, such as by applying a pressure on the sample fluid topush it into sample-receiving chamber 26, and/or creating a vacuum onsample-receiving chamber 26 to pull the sample fluid intosample-receiving chamber 26. In addition, one or more surfaces ofsample-receiving chamber 26 can be formed from a hydrophilic material,provided with a coating of a hydrophilic material, or subjected to ahydrophilicity increasing treatment in order to facilitate filling ofsample-receiving chamber 26 with the test sample.

Test element 10 is configured to detect the presence of, and/or measurethe concentration of, first and second analytes by way ofelectrochemical oxidation and reduction reactions. These reactions aretransduced to an electrical signal that can be correlated to an amountor concentration of the analyte. As shown in FIG. 2, where only somefeatures of test element 10 are illustrated, substrate 16 carries afirst electrode system 32 that includes a plurality of electrodes 34 andelectrode traces 36 terminating in contact pads 38. Electrodes 34 aredefined as those portions of electrode traces 36 that are positionedwithin sample-receiving chamber 26. Substrate 16 also carries a secondelectrode system 46 that includes a plurality of electrodes 48 andelectrode traces 50 terminating in contact pads 52. Electrodes 48 aredefined as those portions of electrode traces 50 that are positionedwithin sample-receiving chamber 26. It should be understood that theillustrated configurations of electrode systems 32, 46 are not limiting,and that alternative configurations are contemplated.

Test element 10 also includes a first reagent material 60 which overliesat least a portion of electrodes 34 of first electrode system 32 withinsample-receiving chamber 26, and a second reagent material 62 whichoverlies at least a portion of electrodes 48 of second electrode system46 within sample-receiving chamber 26. First and second reagentmaterials 60, 62 are suitable for producing electrochemical signals inthe presence of respective first and second test analytes, and aredisposed within sample-receiving chamber 26 in position to provide theelectrochemical signal to electrodes 34, 48 in sample-receiving chamber26. In the illustrated form, a space 64 extends between first and secondreagent materials 60, 62, although forms in which space 64 is absent andfirst and second reagent materials form a continuous layer overelectrodes 34, 48 are also contemplated. Further details regarding firstand second reagent materials 60, 62 will be provided herein below.

Electrodes 34 of first electrode system 32 include a set of measuringelectrodes in the form of working electrode 40 and counter electrode 42which includes portions 44 a and 44 b spaced on opposite sides ofworking electrode 40. As used herein, a “working electrode” is anelectrode at which an analyte is electrooxidized or electroreduced withor without the agency of a redox mediator, while the term “counterelectrode” refers to an electrode that is paired with the workingelectrode and through which passes an electrochemical current equal inmagnitude and opposite in sign to the current passed through the workingelectrode. The term “counter electrode” is meant to include counterelectrodes which also function as reference electrodes (i.e.,counter/reference electrodes). Electrodes 48 of second electrode system46 include a set of measuring electrodes in the form of workingelectrode 54 and counter electrode 56 which includes portions 58 a and58 b spaced on opposite sides of working electrode 54. In thisarrangement, sample-receiving chamber 26 is configured such that samplefluid entering sample-receiving chamber 26 is placed in electrolyticcontact with working electrodes 40 and 54 and counter electrodes 42 and56. This arrangement also allows electrical current to flow between themeasuring electrodes to affect the electrooxidation or electroreductionof the first and second analytes. It should be appreciated however thatthe foregoing is only one of a number of configurations for themeasuring electrodes.

An alternative embodiment test element 110 for assessing first andsecond analytes in a sample is illustrated in FIGS. 3 and 4. Testelement 110 is produced utilizing a head to head manufacturingtechnique. Further details of this technique, and of test element 110generally, are found in International Patent Publication No. WO2012/003306, the contents of which are incorporated herein by referencein their entirety. As illustrated in FIG. 3, electrode patterns 112 arearranged in two columns (one set of electrode patterns in column A andone set in column B) on an elongated layer (tape) of a substrate 114.Test element 110 also includes sample chamber electrode patterns 116located near each other and near the center of substrate 114 and contactpads 118 spaced apart from one another and located near the oppositeedges of substrate 114. In the illustrated form, the electrode patternsare all similar; however in alternative forms at least some of theelectrode patterns may be different from other electrode patterns. Afirst reagent material 120 is applied over the sample chamber electrodes116 in column A and a second reagent material 122 is applied over thesample chamber electrodes 116 in column B.

A spacer layer 124 is attached to the top of substrate 114 with anadhesive layer 126. In the illustrated form, one elongated strip or tapeforms spacer layer 124 to cover the electrode patterns of both columns Aand B, although forms in which two separate strips of spacer layer 124are individually attached to substrate 114 in column A and column B andaligned along centerline 128 are also possible. Spacer layer 124includes a plurality of cutout portions 130 arranged along centerline128. When spacer layer 124 is assembled with substrate 114, cutoutportions 130 will form the perimeters of sample chambers 132 (FIG. 4). Asingle, continuous upper substrate layer 134 is attached to the top ofspacer layer 124 with an adhesive layer 136 and includes a plurality ofvent openings 142, 144 to facilitate venting of sample chambers 132 asthey are filled with a sample fluid. While not previously discussed, itshould be appreciated that adhesive layers 126, 136 include a pluralityof cutout portions 138, 140, respectively, arranged along centerline 128and corresponding to cutout portions 130 of spacer layer 124.Alternatively, it is contemplated that adhesive layer 136 may be a solidlayer without any openings or cutouts.

After substrate 114, reagent materials 120, 122, spacer layer 124 andupper substrate 134 are combined and laminated together, the sheet orroll is separated such that electrodes patterns 116 in columns A and Bremain attached to one another while the test strips in adjacent rows(side-by-side oriented test strips) are separated. In other words, thetest strips in column A are not fully separated from the test strips incolumn B, and test strip pairs are formed with each pair of test stripsarranged in a head-to-head manner. Each test strip pair may be folded toplace contact pads 118 of the test strip from column A adjacent contactpads 118 of the test strip from column B, and to place the sampling endof the test strip from column A adjacent to and facing the samedirection as the sampling end of the test strip from column B. Usingthis type of head-to-head test strip pair, a dual-use biosensor isprovided in which a user can apply a sample of bodily fluid to both teststrips simultaneously in order to test for first and second differentanalytes using a single sample. In one embodiment, a blood filteringmedia may be provided within dual sample chambers 132 prior to foldingthe pair together in order to prevent blood and reagent mixing betweenchambers 132.

It should be appreciated that chambers 132 in each of the head-to-headoriented pair of test strips should be exposed when the pair of teststrips are bent along centerline 128. Alternative manufacturingtechniques can be used to ensure both sample chambers 132 are exposed.For example, in one embodiment, one of the substrate layers, e.g. toplayer 134, is fully separated along centerline 128 during manufacturewhile the substrate 114 is either unmodified or modified to predictablybend about centerline 128. In an alternative embodiment, one of thesubstrate layers is modified, such as through perforations or partialcutting to be easily separated by the user along centerline 128 whilethe other substrate is modified, such as by scoring, denting orcrimping, to predictably bend or separate about a straight line, forexample, centerline 128. In still another embodiment, both top layer 134and lower substrate 114 are modified to allow the head-to-head teststrips to be folded in either direction, i.e., the user may choose tobend the head-to-head pair of test strips to have top layers 134 of thetwo test strips positioned adjacent one another or to have substrates114 of the two test strips positioned adjacent one another.

Substrates 16, 114 may be formed of an insulating material on whichelectrode systems 32, 46 and electrode patterns 112, respectively, arepositioned. Typically, plastics such as vinyl polymers, polyimides,polyesters, and styrenes provide the electrical and structuralproperties which are required. Further, because the test elements can bemass producible from rolls of material, it is desirable that thematerial properties be appropriate to have sufficient flexibility forroll processing, while also giving a useful stiffness to the finishedelement. The material for substrates 16, 114 can be selected as aflexible polymeric material such as polyester, including hightemperature polyester materials; polyethylene naphthalate (PEN); andpolyimide, or mixtures of two or more of these. Polyimides are availablecommercially, for example under the trade name Kapton®, from E.I. duPontde Nemours and Company of Wilmington, Del. (duPont). One specificmaterial possible for substrates 16, 114 is MELINEX® 329 available fromduPont.

The working and counter electrodes, and the remaining portions of theelectrode systems 32, 46 and electrode patterns 112, may be formed froma variety of materials. In one aspect, the electrodes should have arelatively low electrical resistance and should be electrochemicallyinert over the operating range of the test elements. Suitable conductorsfor the working electrode include gold, palladium, platinum, carbon,titanium, ruthenium dioxide, and indium tin oxide, and iridium, as wellas others. The counter electrode may be made of the same or differentmaterials, e.g., silver/silver chloride. In one specific embodiment, theworking and counter electrodes are both gold electrodes.

Electrode systems 32, 46 and electrode patterns 112 may be applied tosubstrates 16, 114, respectively, in any fashion that yields electrodesof adequate conductivity and integrity. Exemplary processes includesputtering and printing, just to provide a few non-limitingpossibilities. In one specific form, gold electrodes are provided bycoating the materials of substrates 16, 114 and then removing selectedportions of the coating to yield the electrode systems 32, 46 andelectrode patterns 112. One particular method for removing portions ofthe coating include laser ablation, and more particularly broad fieldlaser ablation, as disclosed in U.S. Pat. No. 7,073,246, the contents ofwhich are incorporated herein by reference in their entirety.

Laser ablative techniques typically include ablating a single metalliclayer or a multi-layer composition that includes an insulating materialand a conductive material, e.g., a metallic-laminate of a metal layercoated on or laminated to an insulating material. The metallic layer maycontain pure metals, alloys, or other materials, which are metallicconductors. Examples of metals or metallic-like conductors include:aluminum, carbon (such as graphite), cobalt, copper, gallium, gold,indium, nickel, palladium, platinum, silver, titanium, mixtures thereof,and alloys or solid solutions of these materials. In one aspect, thematerials are selected to be essentially unreactive to biologicalsystems, non-limiting examples of which include gold, platinum,palladium, carbon and iridium tin oxide. The metallic layer may be anydesired thickness which, in one particular form, is about 500 nm.

It should be understood that the illustrated form of test elements 10,110 is not-limiting, and that alternative configurations for the dualfunction test elements of the subject application, including thosearranged for optical detection techniques, are also contemplated. Inthis regard, in one additional and non-limiting form a dual functiontest element may include a sandwich-type of configuration where a firstsubstrate that carries a first electrode system is positioned over asecond substrate that carries a second electrode system. The first andsecond substrates are spaced apart from one another by an intermediatelayer that includes a capillary channel or a capillary channel isotherwise formed between the first and second substrates. In thisconfiguration, sample fluid that enters into the capillary channel isdirected toward the first and second electrode systems such thatsimultaneous or near simultaneous covering of the first and secondelectrode systems occurs. While not previously discussed, it should befurther understood that the first substrate is provided with a firstreagent material suited for determination of a first analyte and thatthe second substrate is provided with a second reagent material suitedfor determination of a second analyte. By way of non-limiting example,one technique for producing test elements having this configurationinvolves separately producing the first substrate carrying the firstreagent material and the first electrode system and the second substratecarrying the second reagent material and the second electrode system andthen assembling the first and second substrates together.

In another non-limiting form, a dual function test element may include aslightly different sandwich-type of configuration. In thisconfiguration, a first substrate that carries a first electrode systemis positioned over a second substrate that carries a second electrodesystem. However, the first and second substrates are joined by anadhesive layer and each includes a separate sample chamber positionedover its respective electrode system in lieu of a single capillarychannel. In this form, the test element includes a configuration thatfacilitates simultaneous or near simultaneous filling of the individualsample chambers such that simultaneous or near simultaneous covering ofthe first and second electrode systems also occurs. While not previouslydiscussed, it should be further understood that the first substrate isprovided with a first reagent material suited for determination of afirst analyte and that the second substrate is provided with a secondreagent material suited for determination of a second analyte. This testelement may also be produced utilizing the technique discussed above inconnection with the other sandwich-type of configuration describedherein. Further details of one non-limiting test element having thisform are provided in International Patent Publication No. WO 2012/003306(incorporated herein above).

Further examples of non-limiting arrangements that may be utilized forthe test element of the subject application are disclosed in U.S. Pat.Nos. 6,984,307 and 4,397,956, the contents of which are incorporatedherein by reference in their entirety. It is contemplated that testelements 10, 110 may be useful for the determination of a wide varietyof first and second analytes from a biological fluid. For example, testelements 10, 110 may be readily adapted for use with reagent materials60, 62 and 120, 122 having any suitable chemistry that can be used toassess the presence and/or concentration of the first and secondanalytes. Reagent materials 60, 62 and 120, 122 are operable forreacting with the first and second analytes to produce theelectrochemical signals that represent the presence and/or concentrationof the first and second analytes in the sample fluid. As will bediscussed in greater detail below, reagent materials 60, 62 and 120, 122can include a variety of active components selected to determine thepresence and/or concentration of various first and second analytes. Thetest chemistries of reagent materials 60, 62 and 120, 122 are thereforeselected in respect to the first and second analytes to be assessed.Such analytes may include, for example, glucose, cholesterol, HDLcholesterol, triglycerides, glycerine, lactates, lactate dehydrogenase,malates, alcohol, uric acid, sorbitol, amino acids, 1,5-anhydroglucitoland analytes representative of ketone bodies, such as hydroxybutyrate.In one particular embodiment, test elements 10, 110 include reagentmaterials 60, 62 and 120, 122, respectively, which are selected todetermine the presence and/or concentration of hydroxybutyrate andglucose in blood.

Non-limiting examples of biological fluids in which the first and secondanalytes can be assessed include any bodily fluid in which the analytescan be measured, such as interstitial fluid, tears, urine, and blood.The term “blood” in the context of this document includes whole bloodand its cell-free components, namely plasma and serum. When the testelements are configured for the testing of hydroxybutyrate and glucose,the sample fluid may specifically include, for example, fresh capillaryblood obtained from the finger tip or approved alternate sites (e.g.,forearm, palm, ear lobe, upper arm, calf and thigh), fresh venous bloodor urine. In addition, the test elements may also be useful inconnection with control fluids that are used in conventional fashion toverify the integrity of the system for testing.

The bodily fluid containing the analyte to be assessed may be acquiredand delivered to the test elements in any fashion. For example, a bloodsample may be obtained in conventional fashion by incising the skin,such as with a lancet, and then contacting the test element with fluidthat appears at the skin surface. In one aspect, the test elements areoperable for assessing the targeted analyte while only using very smallfluid samples. Similarly, in one aspect, only a slight skin incision isnecessary to produce the volume of fluid required for the test, and thepain and other concerns with such method can be minimized or eliminated.

Reagent materials 60, 120 include a first coenzyme-dependent enzyme or asubstrate for the first enzyme and a suitable coenzyme. These componentsare typically dissolved or suspended in a matrix. The liquid test samplehydrates or dissolves the matrix, and the first analyte diffuses throughthe matrix to react with one or more of the active components. Suitableenzymes that could be included in reagent materials 60, 120 are forexample dehydrogenases selected from glucose dehydrogenase(E.C.1.1.1.47), lactate dehydrogenase (E.C.1.1.1.27, 1.1.1.28), malatedehydrogenase (E.C.1.1.1.37), glycerol dehydrogenase (E.C.1.1, 1.6),alcohol dehydrogenase (E.C.1.1.1.1), hydroxybutyrate dehydrogenase(HBDH), such as 3-hydroxybutyrate dehydrogenase or beta-hydroxybutyratedehydrogenase, alpha-hydroxybutyrate dehydrogenase andgamma-hydroxybutyrate dehydrogenase, sorbitol dehydrogenase, and aminoacid dehydrogenase e.g. L-amino acid dehydrogenase (E.C.1.4.1.5).Further suitable enzymes are oxidases such as glucose oxidase(E.C.1.1.3.4) or cholesterol oxidase (E.C.1.1.3.6) or aminotransferasessuch as aspartate or alanine aminotransferase, 5′-nucleotidase orcreatine kinase. Depending on the selected enzyme, potential coenzymessuitable for use in reagent materials 60, 120 include FAD, NAD, NADP,thio-NAD, thio-NADP, and a compound according to formula (I)

in which

A=adenine or an analog thereof,

T=in each case independently denotes O or S,

U=in each case independently denotes OH, SH, BH₃ ⁻, or BCNH₂ ⁻,

V=in each case independently denotes OH or a phosphate group,

W=COOR, CON(R)₂, COR, or CSN(R)₂ in which R in each case independentlydenotes H or C₁-C₂-alkyl,

X₁, X₂=in each case independently denote O, CH₂, CHCH₃, C(CH₃)₂, NH, orNCH₃,

Y=NH, S, O, or CH₂,

Z=a residue comprising a cyclic group with 5 C atoms which optionallycontains a heteroatom selected from O, S and N and optionally one ormore substituents, and a residue CR4₂ wherein CR4₂ is bound to thecyclic group and to X₂, and

where R4=in each case independently denotes H, F, Cl, or CH₃, providedthat Z and the pyridine residue are not linked by a glycosidic bond,

or a salt or optionally a reduced form thereof.

In one embodiment, W=CONH₂ or COCH₃.

Exemplary substituents on Z are selected from the group consisting ofOH, F, Cl, and C₁-C₂ alky which are optionally fluorinated orchlorinated and/or OH-substituted, O—C₁-C₂-alkyl.

In another embodiment, a first residue V is OH and a second residue V isa phosphate group. Optionally, the one OH group and the one phosphategroup can form a ring together with the carbon atoms to which they arebound.

Non-limiting examples of adenine analogues include C_(g)-substituted andN₆-substituted adenine, deaza variants such as 7-deaza aza variants suchas 8-aza or combinations such as 7-deaza or 8-aza or carbocyclicanalogues such as formycin where the 7-deaza variants can be substitutedin the 7 position with halogen, C₁-C₆-alkinyl, C_(r) C₆₋alkenyl orC₁-C₆-alkyl. In a further embodiment the compounds contain adenosineanalogues which contain for example 2-methoxydeoxyribose,2′-fluorodeoxy-ribose, hexitol, altritol or polycyclic analogues such asbicyclic, LNA and tricyclic sugars instead of ribose. In one form,(di)phosphate oxygens can also be isoelectronically substituted such asfor example O⁻ by S⁻ and/or by BH₃ ⁻, O by NH, NCH₃ and/or by CH₂ and ═Oby ═S. In one embodiment at least one residue U of a compound accordingto formula (I) is different from OH and in other embodiments at leastone residue U=BH₃ ⁻.

Another more particular but non-limiting compound according to formula(I) in which:

A=adenine,

T=in each case denotes O,

U=in each case denotes OH,

V=in each case denotes OH,

W=CON(R)₂ in which R denotes H,

X₁=O,

X₂=O,

Y=O, and

Z=a carbocyclic 5-membered ring of the general formula (II)

in which a single bond is present between R5′ and R5″, and in which

R4=H,

R5′=CHOH,

R5″=CHOH,

R5=CR4₂,

R6=CH, and

R6′=CH

is carba-NAD or cNAD.carba-NAD has the following structure:

Yet another more particular but non-limiting compound according toformula (I) in which:

A=adenine,

T=in each ease denotes O,

U=in each case denotes OH,

V=in a first case denotes OH and in a second case denotes a phosphategroup,

W=CON(R)₂ in which R denotes H,

X₁=O,

X₂=O,

Y=O, and

Z=a carbocyclic 5-membered ring of the general formula (II)

in which a single bond is present between R5′ and R5″, and in which

R4=H,

R5′=CHOH,

R5″=CHOH,

R5=CR4₂,

R6=CH, and

R6′=CH

is carba-NADP or cNADP.carba-NADP has the following structure:

Other particular but non-limiting compounds according to formula (I)include borano carba-NAD, cyclopentyl NAD, and carba-NAD cyclophosphate.These compounds have the following structures:

Further details regarding compounds according to formula (I) andsynthesis of the same are provided in U.S. Patent Publication No.2008/0231809, the contents of which are incorporated herein by referencein their entirety.

In one embodiment, reagent materials 60, 120 are operable to facilitatedetection of the presence and/or concentration of hydroxybutyrate andinclude a hydroxybutyrate dehydrogenase. Non-limiting examples ofhydroxybutyrate dehydrogenase include alpha-hydroxybutyratedehydrogenase, beta or 3-hydroxybutyrate dehydrogenase, andgamma-hydroxybutyrate dehydrogenase. In one particular form, thehydroxybutyrate dehydrogenase is 3-hydroxybutyrate dehydrogenase. Inthis embodiment, reagent materials 60, 120 further include a coenzymeselected from thio-NAD, thio-NADP, and a compound according to formula(I) or a salt or optionally a reduced form thereof. In one particularform, reagent materials 60, 120 include 3-hydroxybutyrate dehydrogenaseand one of carbaNAD and carbaNADP. In forms where the first reagentmaterial includes a hydroxybutyrate dehydrogenase and a coenzymeselected from thio-NAD, thio-NADP, and a compound according to formula(I) or a salt or optionally a reduced form thereof, it has beensurprisingly discovered that detection of the presence and/orconcentration of hydroxybutyrate can be completed in or about fiveseconds after the test element has been contacted with the sample, whichgenerally corresponds to state of the art glucose testing which takesabout five seconds. Further details in this regard and in connectionwith preparation of related reagent materials are provided in a U.S.Patent Application filed on the same date herewith, entitled “ReagentMaterials and Associated Test Elements” and having Ser. No. 13/667,057,the contents of which are incorporated herein by reference in theirentirety. It should be understood that the use of reagent materials thatrequire more than five seconds to complete detection of the presenceand/or concentration of hydroxybutyrate are also suitable for use intest elements of the subject application.

In addition, while the use of a reagent material that includes ahydroxybutyrate dehydrogenase and a coenzyme selected from thio-NAD,thio-NADP, and a compound according to formula (I) or a salt oroptionally a reduced form thereof has been described herein inconnection with test elements having dual functionalities, it should beunderstood that the use of this reagent material in connection with testelements having single functionality is also possible. Non-limitingexamples of additional forms of test elements for which use of thisreagent material is contemplated are disclosed in U.S. PatentApplication Publication No. 2005/0016844 and U.S. Pat. No. 7,008,799,the contents of which are hereby incorporated herein by reference intheir entirety. It should also be appreciated that the reagent materialdoes not require any additional enzymes, such as diaphorase, to beoperable for the detection of presence and/or concentration ofhydroxybutyrate in forms where it includes a hydroxybutyratedehydrogenase and a coenzyme selected from thio-NAD, thio-NADP, and acompound according to formula (I) or a salt or optionally a reduced formthereof. However, inclusion of additional enzymes within the firstreagent material is also contemplated.

The first reagent material may also include a mediator. The mediator canbe selected as any chemical species (generally electroactive) which canparticipate in a reaction scheme involving the enzyme, the firstanalyte, and the coenzyme, and reaction products thereof, to produce adetectable electroactive reaction product. Typically, participation ofthe mediator in the reaction involves a change in its oxidation state(e.g., a reduction), upon interaction with any one of the first analyte,the enzyme, or the coenzyme, or a species that is a reaction product ofone of these (e.g., a coenzyme reacted to a different oxidation state).A variety of mediators exhibit suitable electrochemical behavior. Amediator can preferably also be stable in its oxidized form, mayoptionally exhibit reversible redox electrochemistry, can preferablyexhibit good solubility in aqueous solutions, and preferably reactsrapidly to produce an electroactive reaction product. Examples ofmediators include benzoquinone, meldola blue, transition metal complexessuch as potassium ferricyanide and osmium derivatives (see InternationalPatent Publication No. WO 98/35225), a phenazine derivative, andhexaammineruthenium chloride or a combination thereof (see U.S. Pat. No.8,008,037). The first reagent material may also include anitrosoaniline-based compound that acts as a mediator precursor (seee.g. U.S. Pat. No. 5,286,362). In this regard, the nitrosoaniline-basedmediator precursor breaks down into reversible mediator components whenit contacts an analyte sample such as blood.

Additional examples of mediators and nitrosoaniline-based mediatorprecursors include N-(2-hydroxyethyl)-N′-p-nitrosophenyl-piperazine,N,N-bis-(2-hydroxyethyl)-p-nitrosoaniline,o-methoxy-[N,N-bis-(2-hydroxyethyl)]-p-nitrosoaniline,p-hydroxynitrosobenzene, N-methyl-N′-(4-nitrosophenyl)-piperazine,p-quinone dioxime, N,N-dimethyl-p-nitrosoaniline,N,N-diethyl-p-nitrosoaniline, N-(4-nitrosophenyl)-morpholine,N-benzyl-N-(5′-carboxypentyl)-p-nitrosoaniline,N,N-dimethyl-4-nitroso-1-naphthylamine,N,N,3-trimethyl-4-nitrosoaniline, N-(2-hydroxyethyl)-5-nitrosoindoline,N,N-bis-(2-hydroxyethyl)-3-chloro-4-nitrosoaniline,2,4-dimethoxy-nitrosobenzene, N,N-bis-(2-methoxyethyl)-4-nitrosoaniline,3-methoxy-4-nitrosophenol,N-(2-hydroxyethyl)-6-nitroso-1,2,3,4-tetrahydroquinoline,N,N-dimethyl-3-chloro-4-nitrosoaniline,N,N-bis-(2-hydroxyethyl)-3-fluoro-4-nitrosoaniline,N,N-bis-(2-hydroxyethyl)-3-methylthio-4-nitrosoaniline,N-(2-hydroxyethyl)-N-(2-(2-methoxyethoxy)-ethyl)-4-nitrosoaniline,N-(2-hydroxyethyl)-N-(3-methoxy-2-hydroxy-1-propyl)-4-nitrosoaniline,N-(2-hydroxyethyl)-N-(3-(2-hydroxyethoxy)-2-hydroxy-1-propyl)-4-nitrosoaniline,and N-(2-hydroxyethyl)-N-(2-(2-hydroxyethoxy)-ethyl)-4-nitrosoaniline.

Reagent materials 62, 122 include a second coenzyme-dependent enzyme ora substrate for the second enzyme and a suitable coenzyme. Thesecomponents are typically dissolved or suspended in a matrix. The liquidtest sample hydrates or dissolves the matrix, and the analyte diffusesthrough the matrix to react with one or more of the active components.Suitable enzymes that could be included in reagent materials 62, 122 arefor example dehydrogenases selected from glucose dehydrogenase(E.C.1.1.1.47), lactate dehydrogenase (E.C.1.1.1.27, 1.1.1.28), malatedehydrogenase (E.C.1.1.1.37), glycerol dehydrogenase (E.C.1.1, 1.6),alcohol dehydrogenase (E.C.1.1.1.1), hydroxybutyrate dehydrogenase(HBDH), such as 3-hydroxybutyrate dehydrogenase or beta-hydroxybutyratedehydrogenase, alpha-hydroxybutyrate dehydrogenase andgamma-hydroxybutyrate dehydrogenase, sorbitol dehydrogenase, and aminoacid dehydrogenase e.g. L-amino acid dehydrogenase (E.C.1.4.1.5).Further suitable enzymes are oxidases such as glucose oxidase(E.C.1.1.3.4) or cholesterol oxidase (E.C.1.1.3.6) or aminotransferasessuch as aspartate or alanine aminotransferase, 5′-nucleotidase orcreatine kinase. Depending on the selected enzyme, potential coenzymessuitable for use in reagent materials 62, 122 include FAD, NAD, NADP,thio-NAD, thio-NADP, and a compound according to formula (I) or a saltor optionally a reduced form thereof.

In one embodiment where reagent materials 60, 120 are operable tofacilitate detection of the presence and/or concentration ofhydroxybutyrate, reagent materials 62, 122 are operable to facilitatedetection of the presence and/or concentration of glucose and include anenzyme for glucose. In one particular form, the enzyme is a glucosedehydrogenase or a glucose oxidase. In this embodiment, reagentmaterials 62, 122 further include a coenzyme selected from FAD, NAD,NADP and the compound according to formula (I) or a salt or optionally areduced form thereof. While not previously discussed, forms in whichreagent materials 60 and 62 have a common coenzyme, e.g., a compoundaccording to formula (I) or a salt or optionally a reduced form thereof,and are merged together to form a single reagent layer such that space64 therebetween is eliminated are contemplated. It should also beunderstood that the reagent materials described herein for detecting thepresence and/or concentration of glucose are not limiting, and thatother forms for the same are known in the art. Additional non-limitingexamples of reagent materials operable for detecting the presence and/orconcentration of glucose are disclosed in U.S. Pat. No. 7,727,467(incorporated herein above) and U.S. Pat. No. 8,008,037, the contents ofwhich are incorporated herein by reference in their entirety. The secondreagent material may also include a mediator. The mediator can beselected as any chemical species (generally electroactive) which canparticipate in a reaction scheme involving the second enzyme, the secondanalyte, and the coenzyme, and reaction products thereof, to produce adetectable electroactive reaction product. Typically, participation ofthe mediator in the reaction involves a change in its oxidation state(e.g., a reduction), upon interaction with any one of the secondanalyte, the second enzyme, or the coenzyme, or a species that is areaction product of one of these (e.g., a coenzyme reacted to adifferent oxidation state). A variety of mediators exhibit suitableelectrochemical behavior. A mediator can preferably also be stable inits oxidized form, may optionally exhibit reversible redoxelectrochemistry, can preferably exhibit good solubility in aqueoussolutions, and preferably reacts rapidly to produce an electroactivereaction product. Examples of mediators include benzoquinone, meldolablue, transition metal complexes such as potassium ferricyanide andosmium derivatives (see International Patent Publication No. WO98/35225), a phenazine derivative, and hexaammineruthenium chloride or acombination thereof (see U.S. Pat. No. 8,008,037). The second reagentmaterial may also include a nitrosoaniline-based compound that acts as amediator precursor (see e.g. U.S. Pat. No. 5,286,362). In this regard,the nitrosoaniline-based mediator precursor breaks down into reversiblemediator components when it contacts an analyte sample such as blood.

Additional examples of mediators and nitrosoaniline-based mediatorprecursors include N-(2-hydroxyethyl)-N′-p-nitrosophenyl-piperazine,N,N-bis-(2-hydroxyethyl)-p-nitrosoaniline,o-methoxy-[N,N-bis-(2-hydroxyethyl)]p-nitrosoaniline,p-hydroxynitrosobenzene, N-methyl-N′-(4-nitrosophenyl)-piperazine,p-quinone dioxime, N,N-dimethyl-p-nitrosoaniline,N,N-diethyl-p-nitrosoaniline, N-(4-nitrosophenyl)-morpholine,N-benzyl-N-(5′-carboxypentyl)-p-nitrosoaniline,N,N-dimethyl-4-nitroso-1-naphthylamine,N,N,3-trimethyl-4-nitrosoaniline, N-(2-hydroxyethyl)-5-nitrosoindoline,N,N-bis-(2-hydroxyethyl)-3-chloro-4-nitrosoaniline,2,4-dimethoxy-nitrosobenzene, N,N-bis-(2-methoxyethyl)-4-nitrosoaniline,3-methoxy-4-nitrosophenol,N-(2-hydroxyethyl)-6-nitroso-1,2,3,4-tetrahydroquinoline,N,N-dimethyl-3-chloro-4-nitrosoaniline,N,N-bis-(2-hydroxyethyl)-3-fluoro-4-nitrosoaniline,N,N-bis-(2-hydroxyethyl)-3-methylthio-4-nitrosoaniline,N-(2-hydroxyethyl)-N-(2-(2-methoxyethoxy)-ethyl)-4-nitrosoaniline,N-(2-hydroxyethyl)-N-(3-methoxy-2-hydroxy-1-propyl)-4-nitrosoaniline,N-(2-hydroxyethyl)-N-(3-(2-hydroxyethoxy)-2-hydroxy-1-propyl)-4-nitrosoaniline, andN-(2-hydroxyethyl)-N-(2-(2-hydroxyethoxy)-ethyl)-4-nitrosoaniline.

The reagent materials may also include a variety of adjuvants to enhancevarious properties or characteristics thereof. See e.g., U.S. Pat. No.7,749,437 referred to hereinabove. For example, reagent materials 60, 62and 120, 122 may include materials to facilitate their placement ontorespective substrates 16, 114 and to improve their adherence thereto, orfor increasing the rate of hydration of the reagent materials by thesample fluid. Additionally, the reagent materials can include componentsselected to enhance the physical properties of the resulting driedreagent layer, and the uptake of a liquid test sample for analysis.Examples of adjuvant materials to be used with the reagent materialsinclude thickeners, viscosity modulators, film formers, stabilizers,buffers, detergents, gelling agents, fillers, film openers, coloringagents, and agents endowing thixotropy.

Non-limiting examples of thickeners that may be included in the reagentmaterials include (1) starches, gums (e.g., pectin, guar gum, locustbean (carob seed) gum, konjac gum, xanthan gum, alginates, and agar),casein, gelatin, and phycocolloids; (2) cellulose and semi-syntheticcellulose derivatives (carboxymethyl-cellulose, methyl cellulose,hydroxymethylcellulose, hydroxyethylcellulose,methylhydroxyethylcellulose); (3) polyvinyl alcohol andcarboxy-vinylates; and (4) bentonite, silicates, and colloidal silica.More specific forms of thickeners include a combination of a xanthan gumsold under the trade name Keltrol F by CP Kelco US, Inc., andcarboxylmethyl cellulose sold under the trade name AQUALON® CMC 7F PH byHercules Inc., Aqualon

Film forming and thixotropic agents that can be included in the reagentmaterials include polymers and silica. One more specific thixotropicagent includes silica sold under the trade name Kieselsaure Sipemate FK320 DS by Degussa AG, while a more specific film forming agent includespolyvinylpyrrolidone, sold under the trademark polyvinylpyrrolidoneKollidon 25, by BASF, and polyvinyl propionate dispersion.

Stabilizers for the enzymes in the reagent materials can be selectedfrom sacchhrides and mono- or di-fatty acid salts. More specificstabilizers include trehalose sold under the trade name D-(+)-Trehalosedihydrate by Sigma Chemical Co. and sodium succinate.

Non-limiting examples of detergents that can be included in the reagentmaterials include water-soluble soaps, as well as water-solublesynthetic surface-active compounds such as alkali, earth alkali oroptionally substituted ammonium salts of higher fatty acids, e.g., oleicor stearic acid, mixtures of natural fatty acids, for example, fromcoconut or tallow oil, fatty sulphates, esters of sulphonic acids, saltsof alkyl sulphonic acids taurine salts of fatty acids, fatty acidamides, and ester amides. More specific forms of detergents include anester amide, n-octanoyl-N-methylglucamide, sold under the trade nameMega-8 by Dojindo Molecular Technologies, Inc., and a fatty acid salt,N-methyl oleyl taurate sodium salt, sold under the trade name GeroponT77 by Rhodia HPCII (Home, Personal Care and Industrial Ingredients).

In one form, the reagent materials are formulated as a viscous solutionthat includes thickeners and thixotropic agents to enhance its physicalproperties. The thickeners are selected to provide a thick, liquidmatrix having the remaining components homogeneously dispersed therein.The thickening and thixotropic agents also inhibit the liquid orsemi-paste material from running or spreading over the surface ofsubstrates 16, 114 after it has been deposited and before it dries.After the reagent materials are deposited, they quickly dry to a readilyhydratable matrix.

As indicated above, it has been surprisingly discovered that detectionof the presence and/or concentration of hydroxybutyrate can be completedin or about five seconds after the test element has been contacted withthe sample in forms where the first reagent material includes ahydroxybutyrate dehydrogenase and a coenzyme selected from thio-NAD,thio-NADP, and a compound according to formula (I) or a salt oroptionally a reduced form thereof. Current state of the art for glucosetesting facilitates the detection of the presence and/or concentrationof glucose to be completed in or about five seconds after the testelement has been contacted with the sample. U.S. Pat. No. 8,008,037describes one non-limiting form of glucose testing that facilitatesdetection of the presence and/or concentration of glucose within thistimeframe. Additional, non-limiting forms of glucose testing thatfacilitates detection of the presence and/or concentration of glucosewithin this timeframe are described in U.S. Pat. Nos. 7,276,146 and7,276,147, the contents of both being hereby incorporated herein byreference in their entirety. It should be understood however that otherreagent materials which facilitate detection of the presence and/orconcentration of glucose within this or other timeframes are known andcould be used in the test elements disclosed herein.

In view of the foregoing, it should be appreciated that detection of thepresence and/or concentration of hydroxybutyrate and glucose can becompleted within five seconds after the test element has been contactedby the sample when the test element includes a first reagent materialthat has a hydroxybutyrate dehydrogenase and a coenzyme selected fromthio-NAD, thio-NADP, and a compound according to formula (I) or a saltor optionally a reduced form thereof, and a second reagent material thatis suitable for detection of glucose and appropriately formulated.However, it should also be understood that variations in the timing forcompleting the detection of hydroxybutyrate and glucose with these testelements is also possible and dependent on, for example, the specificformulation of the reagent materials, amongst other aspects. In one formfor example, the detection of hydroxybutyrate and glucose is completedwithin 10 seconds after the test element has been contacted by thesample. In another form, the detection of hydroxybutyrate and glucose iscompleted within 7.5 seconds after the test element has been contactedby the sample. It should also be appreciated that the timing forcompletion of the hydroxybutyrate detection and the glucose detectionmay be different. For example, in one or more of the foregoing or otherforms the hydroxybutyrate detection is completed within 4 seconds beforeor after completion of the glucose detection. In another variant, thehydroxybutyrate detection is completed within 2 seconds before or aftercompletion of the glucose detection. In still another variant, thehydroxybutyrate detection is completed at or near the same time theglucose detection is completed. It should be understood however thatother variations in the timeframe for completion of hydroxybutyrate andglucose detection are contemplated.

Turning now to FIG. 5, further details of one non-limiting analyticalinstrument in the form of a test meter 210 suitable for use with testelement 10 will be provided. While test meter 210 is described for usewith test element 10, it should be understood that it could be readilyaltered to accommodate use with test element 110 while retaining thegeneral operating principles discussed below. Test meter 210 generallyincludes a controller 212, memory 214 associated with controller 212,and a programmable processor 216 associated with controller 212 andconnected with memory 214. Test meter 210 also includes a display 218connected with processor 216 with, for example, a display driver, andoperable to provide a user readable display of output from processor216. Processor 216 is connected with test element port 224 and operableto process and record data in memory 214 relating to the detection ofthe presence and/or concentration of the first and second analytesobtained through use of test element 10. Test element port 224 includesconnectors 226 configured to engage with contact pads 38 of firstelectrode system 32 and connectors 228 configured to engage with contactpads 52 of second electrode system 46. Test meter 210 further includesuser entry means 220 connected with processor 216 and accessible by auser to provide input to processor 216 and processor 216 is furtherprogrammable to receive input commands from user entry means 220 andprovide an output that responds to the input commands.

Processor 216 is also connected with a communication module or link 222to facilitate wireless transmissions with test meter 210. In one form,communication link 222 may be used to exchange messages, warnings, orother information between test meter 210 and another device or party,such as a caseworker, caregiver, parent, guardian or healthcareprovider, including nurses, pharmacists, primary or secondary carephysicians and emergency medical professionals, just to provide a fewpossibilities. Communication link 222 can also be utilized fordownloading programming updates for test meter 210. By way ofnon-limiting example, communication link 222 may be configured forsending and receiving information through mobile phone standardtechnology, including third-generation (3G) and fourth-generation (4G)technologies, or through Bluetooth, Zigbee, Wibree, ultra-wide band(UWB), wireless local area network (WLAN), General Packet Radio Service(GARS), Worldwide Interoperability for Microwave Access (WiMAX orWiMAN), Wireless Medical Telemetry (WMTS), Wireless Universal Serial Bus(WUSB), Global System for Mobile communications (GSM), Short MessageService (SMS) or WLAN 802.11x standards.

Controller 212 may be comprised of one or more components configured asa single unit or of multi-component form. Controller 212 may beprogrammable, a state logic machine or other type of dedicated hardware,or a hybrid combination of programmable and dedicated hardware. One ormore components of controller 212 may be of the electronic varietydefining digital circuitry, analog circuitry, or both. As an addition oralternative to electronic circuitry, controller 212 may include one ormore mechanical or optical control elements.

In one embodiment including electronic circuitry, controller 212includes an integrated processor 216 operatively coupled to one or moresolid-state memory devices defining, at least in part, memory 214. Forthis embodiment, memory 214 contains operating logic to be executed byprocessor 216 that is a microprocessor and is arranged for reading andwriting of data in memory 214 in accordance with one or more routines ofa program executed by microprocessor 216.

Memory 214 may include one or more types of solid-state electronicmemory and additionally or alternatively may include the magnetic oroptical variety. For example, memory 214 may include solid-stateelectronic Random Access Memory (RAM), Sequentially Accessible Memory(SAM) (such as the First-In, First-Out (FIFO) variety or the Last-InFirst-Out (LIFO) variety), Programmable Read Only Memory (PROM),Electrically Programmable Read Only Memory (EPROM), or ElectricallyErasable Programmable Read Only Memory (EEPROM); or a combination of anyof these types. Also, memory 214 may be volatile, nonvolatile or ahybrid combination of volatile and nonvolatile varieties. Some or all ofmemory 214 can be of a portable type, such as a disk, tape, memorystick, cartridge, code chip or the like. Memory 214 can be at leastpartially integrated with processor 216 and/or may be in the form of oneor more components or units.

In other embodiments, it is contemplated that test meter 210 may utilizea removable memory key that is pluggable into a socket or otherreceiving means (not shown), and which communicates with the memory orcontroller of the meter 210 to provide information relating tocalibration codes, measurement methods, measurement techniques, andinformation management. Examples of such removable memory keys aredisclosed in U.S. Pat. Nos. 5,366,609 and 5,053,199, the disclosures ofwhich are incorporated herein by reference in their entireties.

Controller 212 may also include signal conditioners, filters, limiters,Analog-to-Digital (A/D) converters, Digital-to-Analog (D/A) converters,communication ports, or other types of operators as would occur to thoseskilled in the art. Entry means 220 may be defined by a plurality ofpush-button input devices, although entry means 220 may include one ormore other types of input devices like a keyboard, mouse or otherpointing device, touch screen, touch pad, roller ball, or a voicerecognition input subsystem. Display 218 may include one or more outputmeans like an operator display that can be of a Cathode Ray Tube (CRT)type, Liquid Crystal Display (LCD) type, plasma type, Organic LightEmitting Diode (OLED) type, a printer, or the like. Other input anddisplay means can be included such as loudspeakers, voice generators,voice and speech recognition systems, haptic displays, electronic wiredor wireless communication subsystems, and the like.

As indicated above, test element port 224 includes connectors 226configured to engage with contact pads 38 of first electrode system 32and connectors 228 configured to engage with contact pads 52 of secondelectrode system 46. The connection between test meter 210 and testelement 10 is utilized to apply a potential or a series of potentialsacross the electrodes of first and second electrode systems 32, 46, andto subsequently receive electrochemical signals that are produced byfirst and second reagent materials 60, 62 in the presence of the firstand second analytes and can be correlated to the concentration of thefirst and second analytes. Processor 216 is configured to evaluate theelectrochemical signals in order to assess the presence and/orconcentration of the first and second analytes, and the results of thesame may be stored in memory 214.

While not previously discussed, it should be understood that forms inwhich a first processor is used to evaluate the electrochemical signalsassociated with the first analyte and a second processor is used toevaluate the electrochemical signals associated with the second analyteare contemplated. In addition, when test element 10 is configured forfacilitating electrochemical determination of sample presence and/orthat the amount of the sample fluid is sufficient for testing, processor216 may also be configured to assess electrochemical signals associatedtherewith to determine that the sample fluid has been received by thetest element, and/or that the amount of sample fluid is sufficient fortesting.

In one form, processor 216 is generally configured to automatically orseamlessly produce a signal for providing an indication from meter 210related to the presence and/or concentration of the first and secondanalytes after the relevant electrochemical signals have been evaluated.In certain forms where the first and second analytes are hydroxybutyrateand glucose and the reagent materials are appropriately formulated,processor 216 may be configured such that test meter 210 is capable ofproviding the indication related to hydroxybutyrate and glucose analysisat the same time and with no or only minimal delay after the completionof either test. The indication provided by test meter 210 may be in theform of one or more tactile, aural and/or visual alarms, warnings,messages or other representations, just to provide a few possibilities.For example, in one particular but non-limiting form, processor 216provides a signal to which display 218 is responsive to produce anindication related to the presence and/or concentration of the first andsecond analytes after the relevant electrochemical signals have beenevaluated.

The indication produced by display 218 may include, for example, one ormore of a quantitative indication or representation of the concentrationof one or both of the first and second analytes, a qualitativeindication or representation that one or both of the first and secondanalyte concentrations is acceptable, and a warning indication orrepresentation that one or both of the first and second analyteconcentrations is not acceptable. In this respect, processor 216 isconfigured to compare the measured values for the concentrations of thefirst and second analytes with a predetermined value or range of valuesfor the first and second analytes stored in memory 214 for example, anddetermine if the concentrations of the first and second analytes areacceptable. For example, processor 216 might determine that the measuredconcentration of one or both of the first and second analytes isacceptable if it independently falls below a respective predeterminedvalue or within a respective range of predetermined values, or that theconcentration of one or both of the first and second analytes isunacceptable if it falls above the respective predetermined value oroutside of the respective range of predetermined values. It should beunderstood that a single quantitative, qualitative or warning indicationcould be provided that covers the relevant analysis of the first andsecond analytes or that separate quantitative, qualitative or warningindications could be provided that independently cover the relevantanalysis of the first and second analytes.

The qualitative indication may be in the form of an icon indicative ofapproval, such as a check mark, relevant text, relevant emoticon (e.g.,smiley face), or thumbs up, or in the form of an icon indicative ofdisapproval or unacceptability, such as an “X”-mark, relevant text,relevant emoticon (e.g., frown face), or thumbs down, just to provide afew non-limiting possibilities. Additionally or alternatively, thequalitative indication may involve the use of a first color, shading ordesign of display 218 when the concentration of the first and secondanalytes is acceptable and a second color, shading or design of display218 when the concentration of one or both of the first and secondanalytes is unacceptable. For example, the background of display 218 maybe green when the concentration of the first and second analytes isacceptable and then change to red if and when the concentration of oneor both of the first and second analytes is not acceptable. As anotherexample, the background of display 218 may include a non-patternedconfiguration when the concentration of the first and second analytes isacceptable and a patterned configuration when the concentration of oneor both of the first and second analytes is not acceptable. In stillanother example, display 218 may include a first section associated withanalysis of the first analyte and a second section associated withanalysis of the second analyte. In this arrangement, a color or patternchange of the background of display 218 may be associated with a singleone of the first and second sections in the event only one of the firstand second analyte concentrations is not acceptable. However, a color orpattern change of the background of display 218 will be associated withboth of the first and second sections if the concentration of both ofthe first and second analytes is not acceptable. The first and secondsections may utilize a common color or pattern change, or the color orpattern change associated with the first and second sections could beindependent.

The warning indication may be accompanied by a tactile or aural alarmand/or a notice instructing the user of test meter 210 to seek immediatemedical attention and/or to take one or more actions to address theunacceptable concentration of the first and/or second analytes. In oneform, the warning indication includes an information icon and inresponse to its selection by a user of test meter 210, additionalinformation such as an explanation of the reason for the warning,contact information for one or more healthcare providers or medicalprofessionals, and/or a list of actions that need to be taken due to theunacceptable concentration of one or both of the first and secondanalytes may be provided on display 218. In certain forms, theinformation icon is not provided and this additional information may beautomatically provided without any specific action required of the userof test meter 210.

In addition to or in lieu of display 218 or another component of meter210 producing an indication related to the presence and/or concentrationof the first and second analytes in response to a signal produced byprocessor 216, test meter 210 may be configured to provide theindication related to the presence and/or concentration of the first andsecond analytes to another device or party via communication link 222.In one exemplary form, processor 216 provides a signal to whichcommunication link 222 is responsive to transmit a message includinginformation related to the presence and/or concentration of the firstand second analytes. This message may be sent to one or more otherdevices of the user of test meter 210 and/or to one or more devices ofone or more third parties, such as a healthcare provider, caregiver,parent or guardian, just to provide a few non-limiting possibilities.Non-limiting examples of devices to which this message may be sentinclude PDA's, tablets, computers, pagers, and cellular and landlinephones. In one form, the message may be sent directly to the one or moreother devices of the user of test meter 210 and/or to the one or moredevices of the one or more third parties, although forms in which theuser of test meter 210 is first prompted to transmit the message arealso envisioned. In another form, the message may additionally oralternatively be sent to a central computer or data processing unitwhich may store the message and/or transmit it on to one or more of thevarious devices identified above belonging to the user of test meter 210or one or more other parties.

The information included in the message transmitted by communicationlink 222 may generally correspond to the indication that is describedabove and produced by display 218, and likewise may include one or moreof the quantitative, qualitative and warning indications related to thepresence and/or concentration of one or both of the first and secondanalytes. The devices to which the message is sent by communication link222 may be configured to display this information in a mannercorresponding to that described above in connection with display 218,although forms in which this information is alternatively displayedand/or reproduced are possible. It should be understood however that themessage transmitted by communication link 222 may include information inaddition to or in lieu of these indications. For example, in one formwhere the message is transmitted to a device of a third party, it mayinclude a notice that the user of test meter 210 is in need of emergencymedical assistance. In one particular aspect of this form, the messagemay also include information regarding the location and/or contactinformation of the user of test meter 210. Similarly, the third party towhich the message is sent may directly or indirectly contact or locatethe user of test meter 210 to provide assistance as necessary.Communication link 222 may also be configured to receive input from oneor more of the devices of the one or more third parties. Similarly, inresponse to receiving a message including information related to theconcentration of one or both of the first analytes, such as one or bothof these concentrations not being acceptable, one or more of the thirdparties may send a message to test meter 210 which is received bycommunication link 222 and in turn displayed on display 218. Thismessage may include, for example, directions for the user of test meter210 to contact a third party, such as an emergency medical professional,and/or to take certain actions to correct or otherwise address theunacceptable concentration of one or both of the first analytes. Incertain forms, processor 216 is configured to provide signals orinstructions for execution of different actions or functions by testmeter 210 depending on, for example, the concentration determined forthe first and second analytes. For example, in one form where the firstand second analytes are hydroxybutyrate and glucose, processor 216 isconfigured to automatically or seamlessly provide a signal after therelevant electrochemical signals have been evaluated to which display218 is responsive to produce a quantitative representation of theglucose concentration but not of the hydroxybutyrate or representativeketone concentration. Display 218 could also be responsive to thissignal to further provide a qualitative or warning indication related tothe glucose concentration. Additionally or alternatively, one or moreother components of test meter 210, such as communication link 222,audio speakers or other output means, may be responsive to this signalto provide a quantitative or qualitative output representative of theglucose concentration.

In one aspect of these forms, processor 216 is further configured toprovide a signal for test meter 210 to provide quantitative, qualitativeor warning information related to the measured hydroxybutyrateconcentration. For example, one or more components of test meter 210,such as communication link 220, display 218, audio speakers or otheroutput means, may be responsive to this signal to provide quantitative,qualitative or warning information related to the measuredhydroxybutyrate concentration. In one non-limiting form, display 218 isresponsive to the signal to produce a qualitative or warning indicationrelated to the measured hydroxybutyrate concentration. As illustrated inFIG. 6A for example, display 218 produces a qualitative indication thatincludes a first background color of display 218, such as green, andrelevant text 230 specifying “Ketone OK” when the measuredhydroxybutyrate concentration is acceptable; e.g., it is below apredetermined value or falls within a range of predetermined values.When the measured hydroxybutyrate concentration is not acceptable, e.g.,it is above the predetermined value or falls outside the range ofpredetermined values, display 218 produces a warning indication thatinvolves a change in background color of display 218 from the firstcolor to a second color such as red, and in relevant text 230 to specify“Warning High Ketone (Take Action)”. Display 218 could also provide aquantitative representation of hydroxybutyrate concentration with thewarning indication.

Another variation in displaying the qualitative and warning indicationsrelated to the measured hydroxybutyrate concentration is shown in FIGS.7A and 7B. As illustrated, display 218 includes a first section 232 aassociated with the quantitative representation of the glucoseconcentration, and a second section 232 b associated with thequalitative and warning indications related to the measuredhydroxybutyrate concentration. In this configuration, second section 232b of display 218 produces a qualitative indication that includes a firstbackground color of display 218 at second section 232 b, such as green,and a relevant emoticon 234 a in the form of a smiley face indicating anacceptable hydroxybutyrate concentration when the hydroxybutyrateconcentration is acceptable. When the measured hydroxybutyrateconcentration is not acceptable, second section 232 b of display 218produces a warning indication that involves a change in background colorof display 218 at second section 232 b from the first color to a secondcolor such as red, and from emoticon 234 a to an emoticon 234 bindicative of disapproval, such as a frown face. Display 218 could alsoprovide a quantitative representation of hydroxybutyrate concentrationwith the warning indication in this configuration.

Still, it should be appreciated that other variations in displaying thequalitative and warning indications related to the measuredhydroxybutyrate concentration are possible. In addition, it is alsocontemplated that the qualitative and warning indications related to themeasured hydroxybutyrate concentration could include an information iconthat is selectable by a user of test meter 210. In response to selectingthis icon, test meter 210 provides additional information related to theunacceptable hydroxybutyrate concentration, such as the contactinformation for one or more healthcare providers or medicalprofessionals who should be contacted in light of the unacceptablehydroxybutyrate concentration, and/or a list of actions that need to betaken or activities to avoid in order to correct or otherwise addressthe unacceptable hydroxybutyrate concentration. While not previouslydiscussed, it should also be appreciated that processor 216 may beconfigured to provide a signal to which communication link 222 isresponsive to transmit a message, as described above, related to thequalitative and warning indications associated with the measuredhydroxybutyrate concentration.

In another aspect of forms where, after the relevant electrochemicalsignals have been evaluated, processor 216 is configured toautomatically or seamlessly provide a signal to which one or morecomponents of test meter 210, such as communications link 222, display218, audio speakers or other output means, is responsive to provide aquantitative output representative of the glucose concentration,processor 216 is further configured to produce a signal to which one ormore components of test meter 210 is responsive to provide an outputrelated to the hydroxybutyrate concentration if and only if it is notacceptable; e.g., it is above a predetermined value or falls outside arange of predetermined values. In this configuration, the concentrationof hydroxybutyrate is determined for each test performed by test meter210, but the user of test meter 210 is only bothered or burdened byindications or information related to the hydroxybutyrate concentrationif there is a health concern. In one form however, even in thisconfiguration the system may record into memory or otherwise store boththe glucose and hydroxybutyrate concentrations with appropriate contextsuch as date, time, and marked notes from the user.

In certain embodiments, it is contemplated that access to stored datawould enable meter functionality that would allow the user tographically or in a tabulated format see the results of one or bothanalytes over a period of time such as hours, days, weeks, or months. Incertain aspects of these forms, meter 210 or another device may also beconfigured to monitor for trends in the measured analyte concentrationsthrough review of historical data. Such monitoring may look for avariety of different trends, including for example, trends suggestive ofthe onset or likely onset of DKA and more subtle trends such as higherglucose and/or hydroxybutyrate levels on the weekends and better controlduring the week. In the latter instance, this may be a lifestyle drivenresult and indicate that the patient does not watch or maintain his orher diabetes well during the relevant timeframe, and providing notice ofthe same may help a diabetic user modify their behavior during thesetimes. This advanced functionality that searches or monitors for varioustrends could be a feature of a meter that runs automatically, by requestof the patient or user, or a feature that is managed by a health careprofessional through data that is downloaded to an EMR. Suchretrospective data analysis could also be run on a secondary device suchas a smart phone application that receives the data from the analyticaldevice.

Turning to FIG. 8 for example, test meter 210 is configured such thatdisplay 218 includes a first section 236 where a quantitativerepresentation of the glucose concentration is produced in response tothe signal automatically provided by processor 216. First section 236could also be responsive to this signal to further provide a qualitativeor warning indication related to the glucose concentration. Display 218also includes a second section 238 which is only provided or activatedif and when the hydroxybutyrate concentration is not acceptable. In theillustrated form, the second section 238 provides a warning indicationthat includes relevant text specifying “Ketone High Alert (TakeAction)”. The warning indication of second section 238 also includes adifferent background color relative to that of first section 236. In anon-illustrated from, second section 238 may provide a quantitativerepresentation of hydroxybutyrate concentration in addition to or inlieu of the warning indication if and when the hydroxybutyrateconcentration is not acceptable. Still, it should be appreciated thatother variations in first and second sections 236, 238 of display 218are possible.

In addition, it is also contemplated that second section 238 couldinclude an information icon that is selectable by a user of test meter210. In response to selecting this icon, test meter 210 providesadditional information related to the unacceptable hydroxybutyrateconcentration, such as the contact information for one or morehealthcare providers or medical professionals who should be contacted inlight of the unacceptable hydroxybutyrate concentration, and/or a listof actions that need to be taken to correct or otherwise address theunacceptable hydroxybutyrate concentration. While not previouslydiscussed, it should also be appreciated that processor 216 may beconfigured to provide a signal to which communication link 222 isresponsive to transmit a message, as described above, related to themeasured hydroxybutyrate concentration when it is not acceptable. Forexample, in the form shown in FIG. 9, communication link 222 transmits amessage related to the measured hydroxybutyrate concentration to aseparate device 240 in the form of a cellular phone which may belong tothe user of test meter 210 or a third party. Device 240 could also be ofa form other than a cellular phone, including those listed above, or themessage could be transmitted to a plurality of devices having a varietyof forms and belonging to a variety of different parties. Communicationlink 222 also transmits the message to a central computer or dataprocessing unit 242 that may store the message and/or transmit it on toone or more of the other various devices. It should be appreciated thatforms in which communication link 222 transmits the message to a singleone of device 240 and data processing unit 242 are possible. Inaddition, while the illustrated form shows the message being transmittedin conjunction with the warning indication of second section 238 ofdisplay 218, forms in which the message is transmitted withoutproduction of the warning indication of second section 238 are possible.The information included in the message transmitted by communicationlink 222 may generally correspond to the information displayed bydisplay 218. It should be understood however that the messagetransmitted by communication link 222 may include information inaddition to or in lieu of that displayed by display 218. For example, inone form where the message is transmitted to a device of a third party,it may include a notice that the user of test meter 210 is in need ofemergency medical assistance due to the unacceptable hydroxybutyrateconcentration and the possible onset of an episode of DKA. In oneparticular aspect of this form, the message may also include informationregarding the location (such as by providing GPS coordinates) and/orcontact information of the user of test meter 210. Similarly, the thirdparty to which the message is sent may directly or indirectly contact orlocate the user of test meter 210 to provide assistance as necessary.Communication link 222 may also be configured to receive input orinstructions from one or more of the devices of the one or more thirdparties as discussed above.

In some embodiments, if the hydroxybutyrate level is only slightlyelevated or if the glucose level exceeds a predetermined value, such as˜240 mg/dL, meter 210 may be configured to go into a “ketone watch” modeof recommending and/or prompting a user to test hydroxybutyrate every4-6 hours. In one non-limiting form, upon initiation of and during theketone watch, meter 210 may automatically display measured glucose andhydroxybutyrate levels regardless of their relationship with anypre-specified values. In one embodiment, meter 210 also begins tomonitor for further increases or other notable trends in hydroxybutyratelevels before providing further notice. In such embodiments, thealarm/warning/message notice will only be activated if a sufficientamount of increase from the initial level is measured at subsequentmeasurements. Testing every 4-6 hours is a recommendation from ADAguidelines(http://www.diabetes.org/living-with-diabetes/complications/ketoacidosis-dka.html)if glucose levels exceed ˜240 mg/dL or if a patient is ill (e.g. with acold or the flu).

In further embodiments, meter 210 may be configured to monitor forspecific criteria to activate a “ketone watch dog” mode in order toremind the user to perform tests at some frequency and/or at certaintimes to decrease the likelihood of or avoid an onset of DKA and/or todetect for the same. Noting trends in this direction could enable apatient to avoid full onset of DKA. A dual assay hydroxybutyrate/glucosetest strip enables such a system to be practical and to not burden thediabetic user unless necessary. In yet further embodiments, display 218includes at least one segment in which a visual indication is providedto a user to indicate that meter 210 is in the ketone watch mode orotherwise operating as a “ketone watch dog.”

In addition to or in lieu of the foregoing, and as suggested above,meter 210 may also be further configured to analyze measured glucose orhydroxybutyrate concentrations to monitor for the existence of anytrends. Such trends may include, without limitation, one or more of atrend moving toward a predetermined value or upwardly increasing overtime toward an unacceptable level, trends between common time periodssuch as specific time of day, weekend trends, or after specific eventslike meals, exercise or illness, and any interesting rate-of-changetrends suggesting concerning changes in glucose or hydroxybutyratelevels regardless of whether any such levels are measured to be above apredetermined value. For example, in one non-limiting form test meter210 may be configured to store the results of each hydroxybutyrateconcentration test in memory 214. Processor 216 is structured to analyzethese results by, for example, producing a graphical representation ofthe measured hydroxybutyrate concentrations over time and monitoringfor, amongst others, a trend in the graphical representation toward anunacceptable, predetermined value for the hydroxybutyrate concentration.Upon observing a trend of this nature (e.g. an upward rate of change ofhydroxybutyrate), processor 216 is structured to provide a signal towhich one or more components of test meter 210, such as communicationslink 222, display 218, audio speakers or other output means, isresponsive to provide an output related to the upward trend in thehydroxybutyrate concentration. With reference to FIG. 10A for example,first section 236 of display 218 includes a quantitative representationof the measured glucose concentration and second section 238 of display218 has been provided due to the observation of the upward trend in thehydroxybutyrate concentrations. Second section 238 includes relevanttext specifying “Ketone Trend Noted”. It also includes an informationicon 244 and an emoticon 246 in the form of a frown face indicative ofthe undesired trend in hydroxybutyrate concentration. Forms in whichsecond section 238 of display 218 only includes one or two of therelevant text, information icon 244 and emoticon 246 are also possible.

When information icon 244 is present as illustrated in FIG. 10A, it maybe selected by a user of test meter 210 to provide additionalinformation. For example, in the illustrated form, selection ofinformation icon 244 results in the production of a graphical display248 which shows increasing ketone or hydroxybutyrate levels over time.Graphical display 248 may also be automatically provided in addition toor in lieu of the information of second section 238. Graphical display248 includes ranges representative of normal and high ketone levels,although it should be appreciated that other forms for graphical display248 are possible. Test meter 210 may also provide information inaddition to or in lieu of graphical display 248, including thatdescribed above in connection with the selection of an information icon.It should also be understood that second section 238 of display 218 caninclude a warning indication as described above if and when any testyields an unacceptable hydroxybutyrate concentration.

Moreover, while the provision of an output related to the observation ofan upward trend in hydroxybutyrate concentration has been described inconnection with forms of test meter 210 where output related to thehydroxybutyrate concentration is only provided when the hydroxybutyrateconcentration is not acceptable, it should be appreciated that this typeof output could also be provided in forms where test meter 210 isadditionally or alternatively configured to provide indications relatedto the hydroxybutyrate concentration even when the same is deemedacceptable. For example, in FIG. 10B graphical display 248 isillustrative of an observed trend where measured hydroxybutyrateconcentrations are relatively consistent over time. In FIG. 10C,graphical display 248 is illustrative of an observed trend where anumber of spikes or increases in hydroxybutyrate concentration occurover time, while graphical display 248 in FIG. 10D is illustrative of anobserved trend where measured hydroxybutyrate concentrations are movingtoward an unacceptable value over time. In the case of FIG. 10B,graphical display 248 may provide positive reinforcement to a user oftest meter 210 that their diabetes management is on an acceptable track.In the case of FIG. 10C for example, the observed increases or spikes inmeasured hydroxybutyrate concentrations shown in graphical display 248may correspond to a certain event (such as a meal or exercise) ortimeframe (such as the weekend) and provide notice to a user of meter210 that a different management approach may be necessary at these timesto avoid the intermittent increases. In FIG. 10D, the consistentincrease shown by graphical display 248 provides notice to a user ofmeter 210 that continuing along the current trajectory will result inthe onset of DKA and that remedial actions must be taken to avoid thesame. In FIG. 10E, graphical display 248 shows that the upwardtrajectory has reached above the recommended high level at which DKA islikely imminent, and display 218 provides a clear alert warning thatimmediate action is required.

Despite being described in connection with hydroxybutyrateconcentrations, it should be appreciated that the meter functionalitydiscussed in connection with FIGS. 10A-D and elsewhere is alsoapplicable to measured glucose concentrations. In addition, informationrelated to any observed trend(s) of the hydroxybutyrate or glucoseconcentrations could also be transmitted by communication link 222 toone or more devices belonging to the user of test meter 210 or otherthird parties so that appropriate actions can be taken by necessaryparties to address the observed trend(s).

In view of the foregoing, processor 216 may be structured in variousforms to provide signals or instructions for the execution of certainactions based on the measured hydroxybutyrate concentration. Forexample, and without limitation, processor 216 may be structured suchthat a) the output provided by test meter 210 changes from a qualitativeindication of acceptability of the measured hydroxybutyrateconcentration to a warning indication of unacceptability of the measuredhydroxybutyrate concentration when the hydroxybutyrate concentrationexceeds a predetermined value or falls outside of a predetermined rangeof values; b) test meter 210 only provides an output related to themeasured hydroxybutyrate concentration if and only if it is above apredetermined value or falls outside a range of predetermined values andis therefore not acceptable; and/or c) test meter 210 provides an outputrelated to the observation of an upward trend of hydroxybutyrateconcentrations toward an unacceptable, predetermined value for thehydroxybutyrate concentration. In one aspect, the predetermined valuefor triggering processor 216 to provide signals or instructions for theexecution of certain actions based on the measured hydroxybutyrateconcentration is in the range of 0.6 mM 3.0 mM. In another aspect, thepredetermined value is 0.6 mM. For example, processor 216 may bestructured such that a) the output provided by test meter 210 changesfrom a qualitative indication of acceptability to a warning indicationof unacceptability of the measured hydroxybutyrate concentration whenthe hydroxybutyrate concentration exceeds 0.6 mM; b) test meter 210 onlyprovides an output related to the measured hydroxybutyrate concentrationif and only if it is above 0.6 mM; and/or c) test meter 210 provides anoutput related to the observation of an upward trend of hydroxybutyrateconcentrations toward 0.6 mM.

In another aspect, processor 216 may be structured to provide signals orinstructions for the execution of different actions or functions basedon different hydroxybutyrate concentrations. In one non-limiting formfor example, processor 216 may be configured to provide instructions forprompting execution of certain actions once the hydroxybutyrateconcentration is at or exceeds 0.6 mM and other actions as thehydroxybutyrate concentration continues to rise above 0.6 mM. Forexample, when the hydroxybutyrate concentration is at or exceeds 0.6 mMbut below 1.5 mM, processor 216 may be configured to provideinstructions for activating, amongst other things, warning indicationsrepresentative of an unacceptable ketone or hydroxybutyrateconcentration. If the hydroxybutyrate concentration increases to a levelbetween 1.5 mM and 3 mM, the actions executed in response to theinstructions generated by processor 216 may also further include thetransmittal of a message by communication link 222 to a caregiver,parent, guardian and/or non-emergency medical professional indicating,for example, that a risk is present for developing DKA. Once thehydroxybutyrate concentration reaches 3 mM, the actions executed inresponse to the instructions generated by processor 216 may also furtherinclude the transmittal of a message to an emergency medicalprofessional that the user of test meter 210 requires immediate medicaltreatment. At this stage, the actions executed in response to theinstructions generated by processor 216 may also further includetransmittal of a message to a caregiver, parent, guardian and/ornon-emergency medical professional indicating that the user of testmeter 210 requires immediate medical attention. It should also beunderstood that the values provided above for having processor 216generate instructions for the execution of the various different actionsare exemplary only, and that one or more of the above-described actionsmay be executed in response to different hydroxybutyrate concentrations.

As an illustrative example, for hydroxybutyrate levels less than 0.6 mM,processor 216 in one embodiment is configured to cause conveyance of amessage on display 218 indicating a “low” ketone level and that noaction is required. In other embodiments, at such levels processor 216causes the display to further convey the recommendation to monitorketone change if the user is ill, and/or to perform both glucose andketone tests every 4 hours. In another illustrative example, forhydroxybutyrate levels between 0.6 mM and 1.5 mM, processor 216 in oneembodiment is configured to cause conveyance of a message on display 218indicating a “medium” ketone level, and that a problem may bedeveloping. In other embodiments, at such levels processor 216 causesdisplay 218 to further convey the recommendation to considerinstructions from the user's healthcare provider to notify him/her whensuch levels are detected. In yet another illustrative example, forhydroxybutyrate levels between 1.5 mM and 3.0 mM, processor 216 in oneembodiment is configured to determine whether high glucose levels arealso present and to cause conveyance of a message on display 218recommending the user to contact the healthcare provider immediately. Inyet another illustrative example, for hydroxybutyrate levels above 3.0mM, processor 216 is configured to cause conveyance of a message ondisplay 218 instructing the user to contact the healthcare providerimmediately and/or to proceed to the emergency department of a clinic orhospital.

Additional recommended hydroxybutyrate level guidelines are alsoavailable in the available literature in this regard which can be usedto configure appropriate rules employed by processor 216 for the displayand messaging of a system in accordance with the various embodiments ofthe present invention. For example, according to one literature source,it is opined that under normal circumstances, hydroxybutyrateconcentrations do not exceed 1 mM for Type I diabetic patients. Inpatients exhibiting DKA, the mean hydroxybutyrate concentration is about7 mM but can range between 3 mM and 12 mM. Furthermore, when appropriateaction is taken in response to high hydroxybutyrate concentrations,those concentrations should be expected to fall by 1 mM per hour,otherwise the treatment is likely inadequate and insulin and fluidinfusion rates should be reviewed by the healthcare provider.

In addition to the foregoing, forms are also possible in which processor216 is additionally or alternatively configured to provide instructionsfor executing one or more of the actions discussed above in response todetermining that the hydroxybutyrate concentration is below apredetermined value.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly certain embodiments have been shown and described and that allchanges and modifications that come within the spirit of the inventionsare desired to be protected. It should be understood that while the useof words such as preferable, preferably, preferred or more preferredutilized in the description above indicate that the feature so describedmay be more desirable, it nonetheless may not be necessary andembodiments lacking the same may be contemplated as within the scope ofthe invention, the scope being defined by the claims that follow. Inreading the claims, it is intended that when words such as “a,” “an,”“at least one,” or “at least one portion” are used there is no intentionto limit the claim to only one item unless specifically stated to thecontrary in the claim. When the language “at least a portion” and/or “aportion” is used the item can include a portion and/or the entire itemunless specifically stated to the contrary.

1-23. (canceled)
 24. A method, comprising: performing a plurality oftests to determine concentrations of first and second analytes in asample via a test meter configured to interact with test elements,wherein each of the tests includes applying the sample to a test elementconfigured for electrochemically analyzing the first and second analytesin the sample, and wherein the first analyte is a ketone and the secondanalyte is glucose; storing the first analyte concentration determinedfrom each test performed; analyzing the stored concentrations of thefirst analyte to monitor for an existence of an upwardly increasingtrend in the stored concentrations toward a predetermined value; andproviding a first indication in response to detecting the existence ofthe trend on at least a portion of a display screen of the test meter.25. The method of claim 24, which further includes providing a secondindication in response to determining the first analyte concentration isabove the predetermined value in any one or more of the plurality oftests.
 26. The method of claim 25, which further includes automaticallyproviding a third indication related to the concentration of the secondanalyte after performing each of the tests.
 27. The method of claim 26,wherein the ketone is hydroxybutyrate.
 28. The method of claim 24,wherein the first indication includes one of a graphical illustration ofthe trend and an information icon.
 29. The method of claim 24, whereinproviding the first indication includes displaying an information iconon a meter display.
 30. The method of claim 29, which further includesproviding a graphical illustration of the trend in response to aselection of the information icon. 31-36. (canceled)
 37. The method ofclaim 24, further comprising automatically providing the concentrationof the second analyte on at least a portion of the display screen of thetest meter.
 38. The method of claim 24, wherein the predetermined valueis in a range of about 0.5 mM to about 3.0 mM.
 39. The method of claim38, wherein the predetermined value is about 0.6 mM.